1. Field of the Invention
The present invention relates to a pixel-data selection device to provide motion compensation, and a method thereof, and more particularly, to a pixel-data selection device to provide motion compensation which extracts a plurality of pixel-data by applying a plurality of motion trajectories per block during frame rate conversion, and performs motion compensation by applying a weight to the extracted pixel-data, and a method thereof.
2. Description of the Related Art
Generally, in a PC or an HDTV, frame rate conversion is performed to exchange programs having various broadcasting signal specifications, such as PAL or NTSC. Frame rate conversion refers to converting of a number of frames output per minute. Moreover, in the case where the frame rate increases, a process of interpolating a new frame is required.
Meanwhile, as a broadcasting technology has developed recently, the frame rate conversion is performed after compressing an image data by an image data compressing method, such as a moving picture experts group (MPEG) and an H.263. Especially, in a field of image processing such as the MPEG processing, an image signal usually has redundancy due to high autocorrelation. Therefore, by removing the redundancy while compressing the data, efficiency of data compression can be improved. Here, for effective compression of a video frame which varies according to time, the redundancy in the time-axis direction should be removed.
The removal of the redundancy in the time-axis direction is based on a concept that an amount of data to be transferred is greatly reduced by replacing unchanged portions or moved-but-still-similar portions in a current frame with corresponding portions in an immediately preceding frame.
To make the replacement, it is necessary to find the most similar block between the current frame and a reference frame, which is called “motion estimation.” An indication of an amount of displacement of the block is called a “motion vector.”
One of typical methods to estimate motion vectors is a block matching algorithm (BMA). The BMA is generally used in consideration of precision, real-time processing ability, and hardware implementation and the like.
FIG. 1 is a drawing illustrating a method of estimating motion vectors using a general conventional BMA.
Referring to FIG. 1, Fn−1 is a previous frame/field, Fn is a current frame/field, and Fi is a  frame to be interpolated using the previous frame/field (Fn−1) and the current frame/field (Fn).
The Block Matching Algorithm compares two consecutive images, such as the previous frame/field and the current frame/field, by block units, and estimates one motion vector per block based on an assumption that the pixels in the compared blocks have translational movement. At this time, the motion vector is estimated using a well-known SAD (Sum of Absolute Difference) prediction error. When the motion vector is estimated, motion compensation is performed with respect to the current block (B), i.e., the block to be interpolated using the estimated motion vectors (MV).
However, the conventional method of estimating/compensating the motion may have an incorrect estimation of respective motion vectors estimated by blocks. If the motion compensation is performed with the incorrect motion vectors, block artifacts occur in the interpolation frame/field (Fi), as shown in FIG. 2. In FIG. 2, a solid line represents a true motion vector, and a dotted line is an estimated motion vector. The block artifacts occur since the motion compensation is performed by blocks, and thus the correlation between adjacent blocks at the boarder between the blocks is not considered. A conventional frame rate conversion (FRC) algorithm may employ a nonlinear filter, such as a median filter, to remove the block artifacts. However, the nonlinear filter is not remarkably effective, especially in preventing deterioration of image quality.